An old karate article of mine that I re-wrote

basically just a long ramble about karate punches that i had originally posted on MAP a few years ago. recently re-wrote it completely, corrected a lot of errors and expanded it quite a bit. interested in getting as much diverse feedback as i can. a couple of the links are broken. i'll fix them later today.

"Of Tsuki and Tachi - Observations on breaking people, the Karate way

Greetings and salutations, fellow inhabitants of the internet. For those of you who might not know me, my name is Diego Romero, and I’ve been a regular at MAP forums since december of 2004, under the moniker ‘Fish Of Doom’. I’m a Karateka first and foremost, with my full training time (As of this writing, 9 years and somewhere around 6 months) in Hayashi-Ha Shito-Ryu, holding the rank of shodan in the Style, and with little interest in grading further until I settle down and open a Dojo. I also have some hands-on experience in Shotokan Karate, and a little experience in the Kung Fu styles Bei Shaolin Quan Men and Yang Taijiquan, plus whatever general MA culture I’ve been able to acquire from different sources, MAP foremost among them. This is my third (Or is it the fourth?) revision of this article, the prior ones being mainly editing out mistakes and filling info gaps. This one, on the other hand, will be a full-on re-write, and as I mentioned in my previous editions: “Be warned, for past this very sentence lie ramblings multifarious and generally convoluted analyses the likes of which make heads explode. Read on at your own risk”.

One thing I have noticed, in my years of training and reading about martial arts, is that there is a tremendous amount of disagreement and confusion regarding what is and isn’t a karate punch, or Seiken-zuki. Both Karateka and non-Karateka tend to have rather strong opinions in the matter, so I wish to take as critical a look as I can and try to find a common ground. Feel free to disagree if your school or style does things differently; in fact, I would be supremely interested in debate regarding said differences, in order to increase my general body of knowledge. I only ask that the criticism be constructive. Lack of propriety may well be returned in kind, and with heavy interest rates ;).

So, to start this, let’s first look at the label attached to the punch: ‘Seiken-zuki’. What does this mean?

Some terms in japanese change slightly when at the end of a word compound, for example, Keri (Kick) becomes –geri, Tachi (立ち, contextually ‘[way to] stand’, see 立つ, ‘tatsu’, ‘to stand’) becomes –dachi, and in this case Tsuki becomes –zuki. What we end up with is Seiken, or ‘correct fist’, referring to the specific fist formation used in Karate (Almost universally used to refer specifically to the first knuckle of the index and middle fingers), and –zuki, meaning ‘thrust’, therefore Seiken-zuki means ‘[proper fist] thrust’. This is important to remember, as the proper way to use the fist in Karate weights in significantly in the ideal execution of the movement itself, but more on that later.

The basic Seiken-zuki is, in my opinion, the most fundamental technique present in Karate-Do. It is likely to be the very first technique a beginner will be taught in depth, and in my experience the technique with which most Karate Dojo, or schools (道場, ‘place of the way/road’), start their Kihon (基本, ‘foundation’. contextually: isolated basic technique) training, and I have observed on repeated occasions that almost every Karate Te-waza, or hand/arm technique (手, ‘Te’, ‘hand’, ‘arm’; 技, ‘Waza’, ‘technique’), can be extrapolated from the mechanics of the Tsuki or of the Hikite, or pulling hand (引く, ‘Hiku’, ‘to pull/to tug’;引き, ‘Hiki’, ‘pull/tug’, and 手), which is always trained along with the basic Tsuki. Both the Tsuki and the Hikite will be examined in this article.

Now, as a starting point, let’s examine the Tsuki at its most basic form: the way it would be taught to a beginner on the first day he or she walks into the Dojo. So, let’s get started, shall we?

If you are an aspiring Karateka, one of the first things you will be taught from the repertoire of Karate Waza is, from a natural standing position (Or with parallel feet in some styles, which will later become equally as natural), to extend one arm in front of you, with a closed fist, palm horizontal, fngers facing the floor, and fold your arm to your side (The angle depending on the style, usually with the fist at the height of the hipbone or below your chest), the elbow pointing straight back, the fist resting against your ribs or hipbone and the palm also horizontal, fingers facing upwards. Now comes the big test: you will perform your very first Karate Waza!
You will start by folding the arm that’s extended, bringing the elbow straight back to your ribcage as you flex the elbow, while moving forwards and extending the other arm. When the arms are approximately level with each other (The exact point again varies from style to style), you invert the rotation of the fists (Almost as if turning a steering wheel), as you continue the movement to the position opposite to the one you started in, with the formerly extended arm pulled back, fist at your side, fingers facing upwards, and the formerly folded arm fully extended, fist closed tight, and the fingers facing downwards. The arm that punched performed a Tsuki, while the other performed Hikite.

Congratulations. You have just taken the first step in beginning to learn Karate: you executed a Seiken-Zuki, the most basic and fundamental pillar of this martial art. Hopefully, before your Karate is no more, you will have executed tens of thousands of repetitions of the basic Tsuki.

Now, this was the easy part.

Any able-bodied person can follow the above instructions, and in a certain amount of time, develop a good Tsuki. The basic Tsuki isn’t even needed to develop great punching power. However, train it correctly, understand it, and develop it to a high standard, and the entirety of your Karate will benefit from it.

I will now make a quick review of some of the core technical fundamentals of the Tsuki in its Kihon form, this being fundamental principles isolated into a semi-abstracted and context-less movement. It is these principles that we will later apply when actually punching something or someone.

1 - KEEP THE SHOULDERS DOWN, AND FIRM AGAINST THE TORSO: This is in reality an oversimplification, as the shoulder should ASSIST the movement, but for developing an isolated Kihon Tsuki, lowering the shoulder girdle is the order of the day (With or without significantly abducting the shoulder girdle, which some styles do, like Shotokan). It is done mainly by contracting the Latissimus Dorsi and Serratus Anterior muscles*, which pull the shoulder girdle down and brace it against the torso, for more effective force transfer through postural structure (By this meaning the structure that you create in your torso by adjusting your posture, which is equally as important as the structure your limbs create by moving).

2 - THE PUNCH COMES FROM THE ELBOW, NOT FROM THE FIST: In order to create proper structure for a basic Tsuki, the trajectory has to be as straight as possible. For this, the shoulder joint flexes first, and then rotates medially, mainly through action of the Anterior and Lateral Deltoids, the Pectoralis Major and the Latissimus Dorsi (Along with minor action from other muscles), while the Triceps Brachii extends the elbow joint*. Visualize trying to “push” the fist, with the elbow, and THROUGH a target.

3 - DO NOT TWIST THE WRIST: Twisting the wrist (Forearm pronation*) causes the forearm bones to come out of alignment, and your Seiken will not be properly supported by the elbow nor make contact properly, making your punch less effective and potentially dangerous for your hand. While there IS wrist action during a Tsuki, it is mostly due to a return to a more neutral position during the punch, as the Hikite has the forearm almost completely supinated*, along with a slight abduction in order to fully expose the Seiken, although at a proficient level it integrates with item 4 and can be used to augment the effects of items 1 and 2.

4 - AIM WITH THE SEIKEN: Imagine a straight line running from the crook of your elbow, through the Radius bone and past your wrist. You should align your fist so that the Index finger's knuckle and Metacarpal bone* lie on that line, by, as previously mentioned, bringing the forearm to a neutral position and abducting the wrist slightly. That way, the elbow pushes "into" the seiken as the arm extends. This will only change when we start to deal with variant punches, where the alignment must change to follow the trajectory of the strike.

Now, those four points considered, we can go into some of the more esoteric details of Tsuki-waza (Thrusting techniques).

As we’ve seen, etymologically speaking, it can be said that the term Seiken-zuki does not refer simply to a "punch", but rather to a correctly done punch (According to Karate parameters), where the Seiken is thrust into and through the target. Note however, that this does not necessarily imply that the punch travels exclusively in a straight line (More on that later).

Once one has learned how to do a Tsuki, one is usually taught a stance, or Tachi (-dachi if preceded by another word), from which to throw said punch while moving. In application one uses the principles trained with these stances (Just as one uses the principles trained with the basic Tsuki, not the Tsuki itself) while moving in free-flow, stepping as one sees fit. As always, though, the most basic training is formal and uses isolated abstractions, which also have a certain carry-over in gross motion to certain techniques.

Formal stance-work in Karate can be described as being divided into two stages: a movement stage, where you execute Tai Sabaki (体捌く, roughly ‘body handling’), which is the process by which you move your bodyweight to another location, and usually a technique execution stage, where you finish the Tai Sabaki by focusing that bodyweight, through posture, into a technique. Many people neglect the use of proper Tai Sabaki, focusing on the static posture that forms end of the movement, which usually leads to badly executed and ineffective technique execution. This is extremely wrong, as the static posture at the end of the movement is nothing more than a way of controlling an isolated movement where there is no resistance, and occurs well past the ideal point of a movement’s range of motion where contact should occur, therefore making this neglectful oversight a terrible mistake, as it makes even the strictest repetition practically useless as a means of developing an effective technique. To make a simple analogy, ignoring Tai Sabaki is like placing a basketball under the hoop and claiming that you did a three-point shot, without even throwing the ball, let alone throwing it from behind the three-point line.

Tai Sabaki when applied to a technique is, in a sense, the transition from a soft, relaxed state to the harder, more focused structure required for correct and safe Karate striking. This focused structure is a coordination of “static” posture and limb movement, that connects and redirects as many of the body’s force vectors as possible into the contact surface for a technique. This focus is called ‘Chinkuchi’ in Okinawan Karate. Chinkuchi is the Okinawan translation of the Chinese term Fa Jing (發勁, contextually meaning roughly: ‘expulsion/projection of power*, literally 發, ‘Fa’, ‘emit’ and 勁, ‘Jing’, ‘strong’), which is called Hakkei* in Japanese (発, ‘Hatsu’, ‘to emit’, and 勁, ‘Kei, ’strong’) although to my knowledge functional terminology like Zentai Ryoku (全体力), meaning full-body power (全体, ‘Zen Tai’, ‘whole body’; 力, ‘Ryoku’, ‘power’) is more ofter used to describe this, as the term is not native to Japanese martial arts, and is presumably used in Okinawa due to the influence of Chinese martial artists in the development of Okinawa Te (The precursor of Karate).

Now, before I continue with Chinkuchi, there is a concept in Karate that can be referred to as “Kime” (決め, ‘agreement’, from 決める, ‘Kimeru’; ‘to decide’). There are many definitions and explanations of Kime, some practical, some plainly fantastic, most of purely contextual value given the literal meaning of the word. My definition will also be relative to the context in which I use it (In a way, I simply apply the label Kime to it, as I think it fitting and a consistent bridge between literal meaning and contextual use), so if it does not agree with your own notions, feel free to discard the Kime label and think of this as something else entirely (I am open to terminology suggestions).

As shown here: http://www.karatebyjesse.com/?p=4787, we can see that Kime is a term that is used by the Japanese to say that they have “fixed”, “set” or “agreed on” something. Contextually, one could take the author’s interpretation that kime would refer to the stopping of the technique (As in “it’s agreed that it stops there”, or “the technique is ‘set’ to be like this”), however, I wish to extrapolate this a little. Consider the fact that the term Kime is used colloquially to refer to various physical aspects of the way techniques are executed. Now, it’s generally acknowledged that slow techniques can have (And need) Kime too, so this physical aspect definitely does not refer to brute strength or explosiveness. Additionally, it cannot refer solely to the end point of the technique, since that is nothing more than the point at which the technique ends, which in itself is nothing more than common sense and a safety buffer for your joints, posture and balance (It is literally the point where the follow-through of the movement ends), and does not take into account the technique itself!. What then, could be this aspect that is so ill-defined? One hypothesis, that I happen to share, and which I have also heard expressed by my teacher in Yang Taijiquan and Bei Shaolin Quan, is that Kime is analogous to the Chinese concept of Jing (勁, ‘strong’, ‘Kei’ in Japanese). In Chinese martial arts, there are many theories on strength and it’s use, depending on style and lineage, but they can generally be simplified by reduction to these terms: Li (力, ‘power’, same as japanese ‘Ryoku’), which is brute muscular strength, and its natural extrapolation, Jing, that is the refinement of that muscular strength, by applying Yi (意, ‘mind’, usually contextualized as ‘intent/intention’, ‘I’ in Japanese), resulting in the body adopting as it moves those structures that are optimal for the focusing of the force that it generates. Yi could be described as an analogy for well-developed postural awareness and muscular control combined with good technical awareness, resulting in movements which are done ‘with Yi’ having little if any extraneous movement and being sound in terms of application (As opposed to movements which look “clean” but would not hold up to resistance. By doing a movement with intent, you make your body move exactly in the way it needs to move to do do what you need it to do). By developing Yi, one refines Li, polishing the technique, making it more practical and removing uneeded motions, creating Jing. This is essentially the same concept to which I apply the label Kime now: That attribute that encompasses a technically sound, intentful technique, or, going by the literal definition of the label, one that is performed according to the set parameters of how the technique is to be correctly executed (The formal, institutionalized transmission of which in some cases mutates them over time. The general rule of thumb is that form follows function, and application will reveal what a formal technique’s failings are).

So, we have Kime/Jing, yes? Now we can continue to Chinkuchi, or Fa Jing (Expulsion or projection of Jing). Where any movement can and should express Kime regardless of speed or vigorousness, Chinkuchi is the way a movement should be applied when the intent is to utilize maximum power. It refers to an explosive focusing of Kime, utilizing as much force as possible in as short a time as possible with that coordinated motion, peaking during the impact phase. Now, this is not just speed of the hitting limb. To understand this, let’s take a look (Simplified, as I am neither a physicist nor a kinesiologist) at some (But not all) of the basic forces involved in the performance of a Tsuki:

1 - First, gravity. It pulls your body downwards, and your muscles work passively to hold your skeleton up in an erect posture. This means that there is a permanent downwards force vector in your body, focused on whatever contact point you have with the ground, commonly your feet.

2 - Secondly, the use of your legs to shift your center of mass (Which overlaps with item 1, as you must exert extra force against gravity by pushing against the ground). Your body will always naturally shift so that you are balanced between your contact points with the ground, therefore the way your weight falls can be controlled by shifting your contact points, again generally your feet. Control the way your feet move, and the angles of your leg joints during and after use of footwork, and you control where your entire bodyweight goes.

3 – Third is the use of your core musculature* for stabilization. Your spine is flexible, and to hold its natural curve, it needs a passive pull from your lower back muscles, creating a force that pulls your upper torso back. Proper use of the abdominal wall and hip musculature will counteract this pull and relax your lower back, affirming your core and transmitting force more effectively up to your upper body (And from it during impact), providing a stronger resistance against the counter-force created upon impact. Generally speaking, some styles work specific postures for this (As an example, Goju-ryu and Uechi-ryu in Karate through their Sanchin training, and Taiji and a great amount of “southern” styles like Pak Mei in Chinese martial arts thorugh their posture during basic training), while others do not isolate it in techniques, and work proper structure directly while training against resistance or through supplementary practices like Makiwara striking or Iron Palm training (Shotokan and Shorin-ryu Karate, Bei Shaolin Quan Kung Fu).

4 – Fourth, rotational force: This depends on the technique in question, overlaps with the previous item (As rotation without a firm torso will not transfer as much force to the target after initial contact, although there are techniques that do not require it), and can manifest in multiple ways, for example: Bringing de-aligned hips or upper torso back to a neutral position and hitting at the moment of re-alignment; twisting the upper body explosively(“Waist power”), which can follow from the prior example, and rotating the pelvis (Along with the upper body if item 3 is well developed), which can also lead to one or both of the prior examples. Both of these also overlap with item 2, as it is your leg action that shifts the position of your hips.

5 – Fifth is assistance with the shoulders. Through a slight displacement of the shoulder girdle (Most commonly in Karate, moving the shoulders down and a variable measure forwards, Shotokan emphasizing forwards movement most of all), one eliminates any passive detrimental pull from the upper back muscles as well (So that the pull that remains is synergistic with the movement being performed), and makes the force vectors of the arms converge with the ones coming from the legs, up through the hips, spine and core, and out from the ribcage. Shoulder girdle use (Including rotation of the arm, and thus elbow positioning and strike trajectory) is what ultimately defines where the majority of the force will go once the technique is underway, and is thus perhaps the most important factor determining whether you can apply it with a whole-body structure, regardless on how much force you generate with your motions, although neglecting the previous items will still make your structure weak, no matter how coordinated. This has variable overlap with items 3 and 4, depending on the direction of the technique relative to the ways your torso can rotate or align itself.

6 – The sixth point is the muscular action and structure of your striking arm, pitted against the resistance of the target. This ensures primarily that you deliver the force optimally to the target without destroying your hand. This is performed by aligning the arm in such a way that the wrist always goes towards the Seiken. In a Tsuki, the alignment of the arm must follow the direction in which the punch is going, so that the reaction force from the target goes directly from the second and third metacarpals*, to the wrist, where it can be met from the force from your body supporting your elbow. At the point of impact, the effect depends on the speed at which your Seiken hits, and on the structure of your entire body, which must be strong enough to overcome the reaction force of the target in order to cause damage to it (Which in itself will vary depending on where and how you hit the target).

There are many more factors that will affect a Tsuki (Many of which also overlap with one or more of the others), ranging from the incredibly simple (Relatively speaking), like head position and breathing, to the incredibly complex, like soft tissue deformation and joint compression, but I believe that these 6 that I outlined are among the most fundamental. I would say that if those 6 points are addressed properly in a properly done technique, resulting in it being performed along a correct trajectory, with your entire body structured behind it, reinforcing that trajectory and creating Kime delivered with an explosive motion, you get Chinkuchi/Fa Jing as a result, that being the violent focusing of all the force you can muster into a technique with Kime/Jing, literally projecting it (發, ‘Fa’) in a desired vector with the highest acceleration possible. This is something that can be done in many ways and be employed for many things, with one of the most popular forms being “short power”, commonly known as one-‘cun’ (3.03 cm) power (寸勁, ‘Sun Kei’ in Japanese, ‘Cun Jing’ in Chinese), popularized by Bruce Lee’s famous demonstrations of it with a short-range punch (The widely known ‘one-inch punch’), and also widely used by Chinese styles like Taiji for violent manipulation during grappling techniques, consisting in the application of Chinkuchi/Fa Jing at extremely short distances, ranging from a few centimeters, to emitting force through a surface that is already in contact with the target, usually in one direction first, to create resistance, and then in another to synergize with that resistance and make the target move itself or break.

A very important point to keep in mind regarding the generation of power in techniques is the issue of relaxation. In every given motion of the human body, the muscles referred to as ‘antagonists’, those being the ones that generate the movement opposite to the one being performed, must relax and extend in order to permit the action of the ‘agonists’, which create the movement in question. The resistance created by unreleased contraction of antagonist muscles is called tension, and it directly counteracts the force one wishes to bring to bear during a movement. Training to eliminate tension is a vital element in developing a powerful and effective Tsuki, or any other technique for that matter, as otherwise it results in a massive loss in both acceleration and maximal speed, and reduces the total force that one can focus on the target, as well as weakening one’s structure, for the fact that it not only reduces the force going in the desired vector, but one is also adding the pull of the antagonists to the reaction-force from the impact as well, so if the structure breaks, one’s body will give way at the breaking point (Commonly an arm joint or the lumbar spine, hence the importance of posture and properly coordinated trajectories and alignment).
Two things that I personally found useful in developing my own relaxation for explosive power were a specific idiosyncracy and subsequent visualization during the execution of the Tsuki, and the ability to relax in place. The former consisted in recognizing that only the latter half of the Tsuki corresponds to the impact phase, and that thus the rest of the movement was only delivering the fist from one point to another, subsequently visualizing that the motion did not exist (Imagining that he fist starts at Hikite and Immediately skips to the ‘Chinkuchi phase’, with nothing in-between). The latter consisted in slowly making my movement more efficient in order to move smoothly without tension, massively assisted by Taiji training, which develops this relaxed and smooth efficiency, called ‘Sung’ (鬆,’lax’, ‘loose’, no direct translation in Japanese*). Once you can move without tension, you can coordinate your musculature much better, as only the bare minimum is at use, and you learn to bring it all to bear at once, with proper structure. With time, you can learn to do this explosively while maintaining that coordination and structure (Essentially, the progression is Li/Ryoku > Sung/ > Yi/I > Jing/Kei/Kime > Fa Jing/Kei Hanatsu/Chinkuchi).

Now I’ll talk a bit about application of the Seiken-zuki, although without addressing combat tactics or use of the off-hand, but rather only the act of hitting correctly with the Tsuki, as anything else has to be drilled with a partner in order to be correctly learned (Still, I will talk about the Hikite aspect of Kihon training later on).

Tsuki-waza can come from many angles and work correctly as long as proper alignment relative to the trajectory of the blow is achieved and the punch lands cleanly, with proper observance of the base principles. If you can make use of those principles in any given direction from a given arm posture, then you can strike with a Tsuki in said direction.

That aside, let’s look at how hitting with a Tsuki works:

We’ve seen that power generation starts by using your legs to move as much of your bodyweight as possible. There are a few different ways to do this besides simply shifting in place (That being punching without displacing your feet, including more advanced weight-shifting through foot rotation): The two basic stepping patterns are the normal step, as in the Oi-zuki (追い, ‘chasing’, 突き, ’Tsuki’), and lengthening or shortening your stance without a full-step (Moving either foot). Using these basic stepping patterns, one can focus the technique (Chinkuchi) after the foot lands (The most basic way), at the same time (A more advanced way), or as the foot leaves the floor (The most advanced of the three, requiring that one have, and apply simultaneously, well-trained structure and Tai Sabaki). With sufficient proficiency, well-trained structure, and fast, well-coordinated hands, one will be able to combine multiple Te-waza (Within reason) with a single application of footwork.

While directing one’s bodyweight this way, and augmenting it via muscular action, which generates a structure that focuses all of that force towards one’s striking arm, one shoots out the arm, also with its own support structure bridging the gap between Seiken and torso, and slams the Seiken into the target. One can hit at any point during the execution of the punch, with the most ideal point of contact generally being just past the exact mid-point of the motion because of the alignment and speed the arm reaches in this period, as the arm bones are in an appropriate position to transfer force to each other (In order to resist and overcome the reaction force of the impact), and the agonist muscles have not reached full contraction and thus active insufficiency*, ensuring optimal impact speed and thus a powerful strike, given the presence of correct structure.

But what happens when and as you hit the target? Here is where the four basic principles I mentioned earlier come into play. If at optimal range, you will generally hit with your fist approximately vertical, give or take 15 degrees or so (The exact point, again, depends on what parameters each Karateka uses in execution given the formal technical parameters of his or her style). At this point your shoulder girdle should be coming down and abducting slightly while your shoulder joint flexes, making your elbow move forwards. Now, I mentioned more than once that alignment must follow trajectory, yes? Indeed, as the arm rotates, the fist tweaks its positioning ever so slightly (This is natural in an experienced Karateka due to the way use of the Seiken is trained). This combined arm rotation and wrist adjustment results in the trajectory of the punch not being a straight line but rather a tightly coiled spiral described by the Seiken (Which is standardly of a width that prevents the arm from significatly deviating from a roughly, but not entirely straight line). The presence of this spiral creates a drilling action on impact, finishing with both Seiken and shoulder moving down and into the target. There is debate about the added effectiveness of the twisting, and indeed there are Tsuki variants both without rotation and with inverse rotation, but It is my observation that it is this downwards movement that finally “sets” the body structure in place, and enables the reaction force from the impact to be resisted by the body through redirection towards the ground (What is usually called ‘sinking’) in order to penetrate the target with the strike (I have heard it said on a couple of occasions that an opponent would feel a perfect Tsuki on his or her back if hit on the abdomen). Once sufficient force has been applied such that one can do no more without starting to push, or without breaking structure, the punch is retracted, or the striking arm relaxed, in order to return to free-flow and/or take another action. It is always important to have well-developed structure that can match the force you deliver, lest you end up with what amounts to a collapsible punch that will fold at your weakes structural link. Needless to say, that is bad.

Now, We’re going to move away from application a little, and go over some variants of the basic Tsuki:
I mentioned that the Tsuki is only straight because the spiral the Seiken describes is tightly coiled, yes? Well, if you open up that spiral, your Seiken will move in a wide circle. The wider the spiral, the more overly circular the punch becomes. This is what is called Mawashi-zuki, or ‘turning ‘hrust (, ‘Mawashi’, ‘turning’, from , ‘Mawaru’, ‘to turn’), this being essentially a roundhouse punch. Do remember that the elbow always follows and “pushes” the wrist, and the wrist pushes the Seiken, so in a Mawashi-zuki it will necessarily flare out, and that alignment must follow trajectory, since it must correspond to the force vectors in use in order to create a support structure, thus the wrist will be aligned differently, since the target is hit from from a different angle. Attempting to do Mawashi-zuki with a normal fist alignment will simply result in not hitting cleanly with the Seiken, and risking breaking your hand. A fully executed Mawashi-zuki will have the hand almost vertical (Forearm fully pronated) and the wrist bent back slightly. A shorter and less circular variant of this is called Kagi-zuki (鉤,’Kagi’, ‘hook’) or ‘hook thrust’, and is performed low and almost perpendicular to the body.
Additionally, there are two formal punching techniques that comprise the midpoint and the beginning of the rotation on a Tsuki:
The Ura-zuki (裏, ‘Ura’, ‘inverted’) or ‘inverted thrust’ is performed with the palm facing up, and has a peculiar detail in that, since due to shoulder flexion, the elbow moves up in a circle while still pointing down, the wrist bends (Moving the Seiken downwards), as a normal fist alignment would risk collapsing the wrist on impact. Aside from that, it is almost identical to the normal Seiken-zuki, having the point of focus approximately when the elbow has moved past the torso (The arm then extends fully and is retracted). It is generally performed from closer in and can be used to effectively attack upwards as well (Using the wrist flick and arm extension to tilt an opponent’s head back explosively).
Following from this we find the Tate-zuki (縦, ‘Tate’, ‘vertical’), which, as the name indicates, is performed when the fist is vertical, without rotating further. This punch is also delivered with the elbow down, but with the forearm in a neutral position as opposed to the supination in the Ura-zuki. Additionally, the wrist must abduct slightly in order to expose the Seiken and avoid significant contact with the ring and pinky finger’s knuckles. This produces an interesting effect, in that the entire arm can be “dropped” on the target, by moving the shoulder, elbow, wrist and Seiken downwards simultaneously a very short distance, resulting in a considerably strong arm structure that is very suited for delivery of Sun Kei/Cun Jing when refined to a high standard, although it lacks the versatility of punching with medial rotation as regarding angles of attack and circular strikes.
A last detail worth mentioning regarding the use of both Ura and Tate punches is that they can also be employed using the opposite rotation to that of the common Tsuki, that being external arm rotation and forearm supination, which helps give both punches that extra oomph when the space is available (As the external rotation helps drops the elbow, helping contract the relevant musculature), at little cost to the puncher.

Okay, still with me? Good, because this is where the freaky stuff starts. We've gone over Kihon principles, Kime and Chinkuchi, use of Tai Sabaki, power generation, Tsuki variants and even etymology. Now I’ll share some more conclusions and hypotheses about the Tsuki and related subjects:

First of all, if you have bulging veins in your forearms, get the blood blowing and check out this beauty in your forearm:

If you scrutinize vein and arm correctly, you will notice that when your arm is extended at the end of a Tsuki, the basilic vein follows approximately the same path your Seiken must travel to get back to Hikite (Note: some styles of karate rotate the arm a bit later, in which case thie would not apply perfectly, but the principle is still the same).

Speaking of the Hikite, here are my thoughts on it:

The Hikite is quite obviously a training tool and not a fighting method, even more so than the Kihon Seiken Tsuki, but what does it do? Let’s look at it from a few different angles, shall we?

First of all, the Hikite can be said to be the exact opposite of a Tsuki. Pronation vs. supination, elbow extension vs. elbow flexion, shoulder flexion vs. shoulder extension, even the shoulder girdle is pulled back instead of forwards. What can we infer from this? We have seen that the entire body is involved in the proper structure for a Tsuki, yes? Well, by starting the punch from the complete opposite of its “business end”, you train the body (Taking as a given that the Tsuki is performed and trained correctly, including with resistance, of course) to assume the entirety of that structure at once, which will later benefit you when you shorten the motion for application, and later for the development of short power, by strengthening and helping activate those structure generating muscles that already have a certain degree of activation (And thus usually active insufficiency) when one is in a normal fighting posture, and that activate only on impact, as stabilizers
Secondly, It is commonly known that excessive contraction of a muscle can cause tightness in it, and a serious Karateka will spend years, if not decades, training the Tsuki and exercises to supplement it, among them arm exercises that resemble it, like push-ups and bench presses. An excess of these can shorten the muscles of the shoulders and chest, therefore something is needed to balance them. The Hikite is a tremendously convenient way to do this, as it is done this way on almost every basic technique, therefore ensuring proper maintenance of shoulder health if it is done correctly, as well as promoting muscle use in the upper back.
Third, we have the name itself, which means pulling hand. This is pretty straightforward: You pull with your hand. Preferably while hitting with the other one. This is obviously not something that will be done with every single move in combat, but it trains the gross motion for when it’s needed.
Fourth is the fact that Hikite is essentially bringing your elbow sharply backwards. In other words, a backwards elbow strike. Although a Karate technique, these are almost non-existent in Karate Kihon, presumably because you train them in 99% of everything you do within Kihon.

In addition to these four aspects, in the same way in which it works the backwards elbow, the combination of Hikite and Tsuki works all of the arm motions involved in Karate Te-waza, and if we include supinating Ura-zuki and Tate-zuki, the Tsuki by themselves will work all of the arm motions involved in the basic Uke-waza (‘Receiving techniques’, the actual term for “blocks”, from 受ける, ‘Ukeru’, ‘to receive’) .
In fact, these basic Uke-waza have gross motions so similar to those of the Tsuki variants that not only weill they benefit if you train your Tsuki (Although of course the Uke-waza themselves must not be neglexted), but they themselves can also be used as variant Tsuki, for example the rising “block” as a short Mawashi-zuki (Particularly for styles that do it with the elbow extended well past 90º), like the Kosa-zuki that Dan Djurdevic Sensei describes in his chambering article*, whereas inside and outside blocks can be used as supinating Ura-zuki to strike high at the same time as one parries, and low sweeping blocks can be turned into a more coiling and expansive motion and used to punch low. This is particularly viable if one has developed short power, as it enables one to attack in very compact motions and move further away from techniques and towards pure principles.

Now, I believe I have established almost everything worth knowing about the basic Karate punching technique. In closing, let us recap the correct technique pointers for a Tsuki. What are these? Affirm your shoulder and assist the movement with it, mind your elbow to secure your structure firmly at its most common weak point, align your fist correctly to protect your wrist, and aim with the seiken for optimal force transference. The same four points I outlined for the isolated kihon tsuki at the beginning of the article, and the same basic principles that, given proper power generation, will let you carve a path of mayhem and destruction through your opponents. It is truly fearsome, the Seiken-zuki.